Detection, quantification, isolation and purification of target biomaterials, such as viruses and biomacromolecules (including constituents or products of living cells, for example, proteins, carbohydrates, lipids, and nucleic acids) have long been objectives of investigators. Detection and quantification are important diagnostically, for example, as indicators of various physiological conditions such as diseases. Isolation and purification of biomacromolecules, such as monoclonal antibodies, produced from cell cultures are important for therapeutic and in biomedical research. Biomacromolecules such as enzymes have been isolated, purified, and then utilized for the production of sweeteners, antibiotics, and a variety of organic compounds such as ethanol, acetic acid, lysine, aspartic acid, and biologically useful products such as antibodies and steroids.
Chromatographic separation and purification operations can be performed on biological product mixtures, based on the interchange of a solute between a moving phase, which can be a gas or liquid, and a stationary phase. Separation of various solutes of the solution mixture is accomplished because of varying binding interactions of each solute with the stationary phase; stronger binding interactions generally result in longer retention times when subjected to the dissociation or displacement effects of a mobile phase compared to solutes which interact less strongly and, in this fashion, separation and purification can be effected.
Most current capture or purification chromatography is done via conventional column techniques. These techniques have severe bottlenecking issues in downstream purification, as the throughput using chromatography is low. Attempts to alleviate these issues include increasing the diameter of the chromatography column, but this in turn creates challenges due to difficulties of packing the columns effectively and reproducibly. Larger column diameters also increase the occurrence of problematic channeling. Also, in a conventional chromatographic column, the absorption operation is conducted until a pre-determined loading of the resin with the binding chemical species, so as to not have breakthrough of the species; this is done either to prevent loss of valuable product, or to prevent contaminants from continuing to remain in the flow-through). This causes the dynamic or effective capacity of the adsorption media to be significantly less than the overall or static capacity.
When using a selective Protein A column, small amounts of contamination remaining after the primary capture steps will bind to the Protein A resin in the column. This contamination, albeit at a low concentration, will be released during product elution. The product fluid stream will need to be “polished” to remove the trace impurities such as host cell proteins and viruses to make a safe viable pharmaceutical or biological product.
Polymeric resins are widely used for the separation and purification of various target compounds. For example, polymeric resins can be used to purify or separate a target compound based on the presence of an ionic group, based on the size of the target compound, based on a hydrophobic interaction, based on an affinity interaction, or based on the formation of a covalent bond. There is a need in the art for functionalized membranes that overcome limitations in diffusion and binding, and that may be operated at high throughput and at lower pressure drops. There is a need in the art for polymeric substrates having enhanced affinity for selective removal of biocontaminates, such host cell proteins, cell debris, DNA fragments, viruses and cell debris from biological feed-streams in the production of monoclonal antibodies. There is also the need to have functionalized structures that overcome diffusion and productivity limitations in bind-and-elute operations, wherein the valuable antibody product is bound to a ligand so as to allow clearance of impurities such as leached Protein A, to be eluted after a predetermined loading of the antibody is reached.